1. Field of the Invention
The present invention relates to a display device. In particular, the present invention relates to display devices capable of displaying three-dimensional (3D) images.
2. Description of the Related Art
Display devices are widely used, ranging from large display devices such as television devices to small display devices such as mobile phones. From now on, products with higher added values will be needed and are being developed. In recent years, display devices that can display 3D images have been developed in order to display more realistic images.
As methods for displaying 3D images, there are a method using glasses for separating an image seen with a left eye and an image seen with a right eye (also referred to as stereoscopy), and autostreoscopy by which 3D images can be seen by the naked eye by addition of a structure for separating an image seen with a left eye and an image seen with a right eye in a display portion. It is not necessary to prepare glasses to see autostreoscopic 3D images, which offers a high convenience. Autostereoscopic 3D display is coming into widespread use such as mobile phones and mobile game consoles.
As a method for displaying autostreoscopic 3D images, there is known a parallax barrier method in which a parallax bather is added to a display portion. A parallax barrier for the parallax barrier method is a stripe-shaped light-shielding portion and causes a decrease in resolution when display is switched from 3D display to 2D display. In view of this, for the parallax barrier method, there is suggested a structure in which a liquid crystal panel having a patterned transparent electrode is used for switching between 2D display and 3D display (see Patent Document 1). In that case, transmission or shielding of light by a liquid crystal layer can be controlled by controlling voltage applied to the transparent electrode in order to set the presence or absence of a parallax barrier.
Moreover, there are mobile phones and the like in which a direction in which a parallax barrier is arranged is changed when an orientation of a display portion with respect to a viewer is changed.